In the past, there have been proposed various light source devices as backlights of liquid crystal display (LCD: Liquid Crystal Display) devices, which are used in liquid crystal display televisions, laptop personal computers, car navigation systems, etc. (for example, see Patent Documents 1 to 3). Each of the light sources described in these Patent Documents employs an edge light method utilizing a light guiding means. However, reduction in thickness and increase in area of the liquid crystal display devices are in progress in recent years, and development of a direct-under type light source, capable of achieving the reduction in thickness and the increase in area, has also been desired in the backlight mounted thereon.
Accordingly, a light source device illustrated in FIGS. 16(A) and (B) for example has been proposed as the direct-under type backlight. As illustrated in FIG. 16(A), this light source device arranges point sources of light 110, emitting a white light, on a substrate 100 at regular intervals, and arranges a diffusion plate 120 etc. thereabove, to allow a uniform surface light-emission.
As illustrated in FIG. 16(B), in the point source of light 110 described above, an insulant 112, an electrode 113, a thermal conductive bonding layer 114, and a sub-mount substrate 116 are arranged on a metal plate 111. A blue light emitting diode (LED: Light Emitting Diode) 117 as an excitation light source is formed on the sub-mount substrate 116. The blue light emitting diode 117 is connected to the electrode 113 via a bonding wire 115. In addition, a phosphor layer 118 is applied and formed so as to cover the blue light emitting diode 117. An entire body thereof is packaged by a seal layer 119. With this configuration, a blue light emitted from the blue light emitting diode 117 is converted into a red light and a green light, or into a yellow light in the phosphor layer 118, and thereby a white light is output by the point source of light 110 as a whole.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2003-100126    Patent Document 2: Japanese Unexamined Patent Application Publication No. 2003-222861    Patent Document 3: Japanese Unexamined Patent Application Publication No. 2001-23420